1. Field of the Invention
This invention relates generally to engines connected to driven devices, such as oil and gas well pumps, through a clutch mechanism. The invention relates more particularly to an apparatus for mechanically engaging and disengaging the clutch from the engine.
2. Description of the Related Art
It is well known in the field of oil and gas drilling and pumping to drill an oil or gas well and then place a pump at the well to pump oil or gas out of the well. The pumps of oil and gas wells are commonly driven by gasoline, or even more conveniently, natural gas engines. Natural gas is often plentiful at oil and gas wells, and can be used to fuel an internal combustion engine, for example, to drive the pump.
The conventional pump has an engine drivingly linked to the pump, and the engine is turned on by an operator who starts the engine and then drivingly links the engine to the pump. The engine pumps for as long as the engine's fuel lasts, or for some other set period, it turns off, and then the pump stops operating.
Because oil and gas wells are often in remote locations, it is common to start the engine to drive the pump, and then return long after the engine runs out of fuel or ceases operation for some other reason. This arrangement avoids a situation in which operators must remain present at all pumps to oversee their operation, but has the distinct disadvantage of pumping too little fluid from the well. This arises due to the fact that pumping fluids from a well for a few hours every day in a month is much more effective than pumping fluids for only 20 consecutive hours in a month.
More recently, controllers were invented to operate engines a few hours per day over the course of a month. These controllers work well when the engine and pump can be completely controlled electronically. However, many larger pumps and engines cannot be controlled only electronically, due, in particular, to heavy clutch mechanisms. The only existing solution to the problem is for the human operator to engage the clutch mechanism manually upon startup of the engine, and return later when the engine is about to shut off, and manually disengage the engine from the pump.
Recently, an automatic starting system for such fluid pumping engines has become known. For example, Arrow Engine Company has an Auto Start System that uses an electric motor with a worm gear that drives a drive shaft along a longitudinal path. That drive shaft has a collar that fits over the end of the lever arm for a conventional manual clutch actuator. The drive shaft drives the lever arm in one direction for engaging the clutch, and in the opposite direction for disengaging the clutch. This mechanism has a tendency to destroy the clutch, because it continues to apply the clutch-engaging force even after the clutch has begun to engage. This causes the clutch to wear out prematurely, and interferes with the manual actuation of the clutch.
Therefore, there is a need for an automatic (i.e., non-manual) clutch actuator apparatus that avoids the need for constant human oversight of oil wells, but does not cause premature wear on clutches.